Originally Posted by dwanthny
I too have a metadata.opf in the root of my library. The last time I just deleted it but your question intrigued me so I checked it out prior to deleting it. It turns out it was the last book I added to my library. I'm not sure why calibre stashed it there. Maybe I'll be able to develop a trend as I find these files.
Huh, you're right. I have one of those as well. It contains metadata of the last added book, as in your case. Maybe we should wait for Kovid or someone to explain that...